Task-Oriented Conversation Generation Using Heterogeneous Memory Networks

How to incorporate external knowledge into a neural dialogue model is critically important for dialogue systems to behave like real humans. To handle this problem, memory networks are usually a great choice and a promising way. However, existing memory networks do not perform well when leveraging heterogeneous information from different sources. In this paper, we propose a novel and versatile external memory networks called Heterogeneous Memory Networks (HMNs), to simultaneously utilize user utterances, dialogue history and background knowledge tuples. In our method, historical sequential dialogues are encoded and stored into the context-aware memory enhanced by gating mechanism while grounding knowledge tuples are encoded and stored into the context-free memory. During decoding, the decoder augmented with HMNs recurrently selects each word in one response utterance from these two memories and a general vocabulary. Experimental results on multiple real-world datasets show that HMNs significantly outperform the state-of-the-art data-driven task-oriented dialogue models in most domains.Comment: Accepted as a long paper at EMNLP-IJCNLP 201

Enhanced Light Utilization in Semitransparent Organic Photovoltaics Using an Optical Outcoupling Architecture

Buildingâ integrated photovoltaics employing transparent photovoltaic cells on window panes provide an opportunity to convert solar energy to electricity rather than generating waste heat. Semitransparent organic photovoltaic cells (STâ OPVs) that utilize a nonfullerene acceptorâ based nearâ infrared (NIR) absorbing ternary cell combined with a thin, semitransparent, high conductivity Cuâ Ag alloy electrode are demonstrated. A combination of optical outcoupling and antireflection coatings leads to enhanced visible transmission, while reflecting the NIR back into the cell where it is absorbed. This combination of coatings results in doubling of the light utilization efficiency (LUE), which is equal to the product of the power conversion efficiency (PCE) and the average photopic transparency, compared with a conventional semitransparent cell lacking these coatings. A maximum LUE = 3.56 ± 0.11% is achieved for an STâ OPV with a PCE = 8.0 ± 0.2% at 1 sun, reference AM1.5G spectrum. Moreover, neutral colored STâ OPVs are also demonstrated, with LUE = 2.56 ± 0.2%, along with Commission Internationale d’Eclairage chromaticity coordinates of CIE = (0.337, 0.349) and a color rendering index of CRI = 87.An efficient and neutral colored semitransparent organic photovoltaic cell (STâ OPV) is realized by utilizing a nearâ infrared (NIR) absorbing ternary cell combined with a thin, semitransparent, highâ conductivity Cuâ Ag alloy electrode. A combination of optical outcoupling and antireflection coatings leads to enhanced visible transmission, while reflecting the NIR back into the cell where it is absorbed.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151812/1/adma201903173.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151812/2/adma201903173_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151812/3/adma201903173-sup-0001-S1.pd

Suggestions on the development strategy of shale gas in China

AbstractFrom the aspects of shale gas resource condition, main exploration and development progress, important breakthrough in key technologies and equipment, this paper systematically summarized and analyzed current situation of shale gas development in China and pointed out five big challenges such as misunderstandings, lower implementation degree and higher economic uncertainty of shale gas resource, and still no breakthrough in exploration and development core technologies and equipment for shale gas buried depth more than 3500 m, higher cost and other non-technical factors that restrict the development pace. Aiming at the above challenges, we put forward five suggestions to promote the shale gas development in China: (1) Make strategies and set goals according to our national conditions and exploration and development stages. That is, make sure to realize shale gas annual production of 20 × 109 m3, and strives to reach 30 × 109 m3. (2) Attach importance to the research of accumulation and enrichment geological theory and exploration & development key engineering technologies for lower production and lower pressure marine shale gas reservoir, and at the same time orderly promote the construction of non-marine shale gas exploration & development demonstration areas. (3) The government should introduce further policies and set special innovation funds to support the companies to carry out research and development of related technologies and equipment, especially to strengthen the research and development of technology, equipment and process for shale gas bellow 3500 m in order to achieve breakthrough in deep shale gas. (4) Continue to promote the geological theory, innovation in technology and management, and strengthen cost control on drilling, fracturing and the whole process in order to realize efficient, economic and scale development of China's shale gas. (5) Reform the mining rights management system, establish information platform of shale gas exploration and development data, and correctly guide the non-oil and gas companies to participate in shale gas exploration and development

An insight into the mechanism and evolution of shale reservoir characteristics with over-high maturity

AbstractOver-high maturity is one of the most vital characteristics of marine organic-rich shale reservoirs from the Lower Paleozoic in the south part of China. The organic matter (OM) in shale gas reservoirs almost went through the entire thermal evolution. During this wide span, a great amount of hydrocarbon was available and numerous pores were observed within the OM including kerogen and solid bitumen/pyrobitumen. These nanopores in solid bitumen/pyrobitumen can be identified using SEM. The imaging can be dissected and understood better based on the sequence of diagenesis and hydrocarbon charge with the shape of OM and pores. In terms of the maturity process showed by the various typical cases, the main effects of the relationship between the reservoir porosity and organic carbon abundance are interpreted as follows: the change and mechanism of reservoirs properties due to thermal evolution are explored, such as gas carbon isotope from partial to complete rollover zone, wettability alteration from water-wet to oil-wet and then water-wet pore surface again, electrical resistivity reversal from the increasing to decreasing stage, and nonlinearity fluctuation of rock elasticity anisotropy. These indicate a possible evolution pathway for shale gas reservoirs from the Lower Paleozoic in the southern China, as well as the general transformation processes between different shale reservoirs in thermal stages

Device Physics and Applications of Ternary Organic Photovoltaics

Organic photovoltaics (OPVs) are emerging as an attractive candidate for solar energy harvesting due to their advantages in environmental compatibility, low-cost, flexibility and transparency. The past few decades have witnessed substantial development in innovative molecular and device architecture designs to improve the performance of OPVs. The ternary bulk heterojunction (BHJ) devices stand out as one of the most widely employed strategies due to their broad absorption, efficient photocurrent generation and simple fabrication process. This thesis explores the working principles of ternary OPVs and demonstrates their application in high efficiency and scalable OPV devices. The first part of the thesis focuses on the photogeneration process in ternary OPVs. We test the validity of the concept of “molecular alloy” by investigating the optoelectronic properties of a representative ternary system. Furthermore, we show that the end-capping exchange reaction between acceptor-donor-acceptor type of non-fullerene acceptors (NFAs) generates up to four unexpected molecular species in the ternary BHJs, leading to reduced reproducibility and reliability of OPV devices. The dipolar reaction products of the end-capping exchange are shown to reorient over time and impact the dielectric properties and device performance. In the second part, we present the application of ternary OPVs in multi-junction devices and semitransparent modules. With the extended absorption in near-infrared (NIR) provided by a ternary sub-cell, we demonstrate high efficiency tandem OPV device. In addition, it is essential to develop a scalable fabrication process of modules to commercialize OPV technology. We study the resistance loss when scaling up semitransparent OPV (ST-OPV) devices and demonstrate ultrafine metal grid structure in a prototype module to realize negligible efficiency loss from series resistance. Moreover, we introduce a high resolution, non-destructive multilevel peel-off patterning method in the fabrication of ST-OPV modules. Combined with a NIR-absorbing ternary BHJ, the ST-OPV mini-module simultaneously achieves high light utilization efficiency and geometric fill factor. The demonstrations in this dissertation provide insight to further understand the mechanisms, and then advance the application of ternary OPVs.PhDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/192339/1/xjhuang_1.pd

Real-Time Localization Method of Large Pressure Vessel Leaks Based on Improved CNN and STCA of Elastic Wavefield

In this paper, a real-time leak source localization method based on convolutional neural network (CNN) of elastic wavefield images and spatio-temporal correlation analysis (STCA) is developed for the pressure vessel leakage. This method uses a single sensor array coupled to the wall to collect the elastic wave data excited by the leak source. Besides, the distance $R$ and the direction $\theta$ between the leak source and the sensor array are calculated based on CNN and STCA respectively, to finally obtain the location ( $R$ , $\theta$ ) of the leak source. In this paper, the digital twin model of the experimental platform is established, the training set is obtained by the finite element simulation, and the CNN model applied to the elastic wavefield images is studied and constructed. The experimental results show that the maximum locating error is 1.46 cm and the average locating error is about 0.56 cm within the range of a 1 m2 experimental plate based on the method proposed in this paper